ACPI: Fix the incorrect calculation about C-state idle time
authorZhao Yakui <yakui.zhao@intel.com>
Wed, 2 Jun 2010 03:04:09 +0000 (11:04 +0800)
committerLen Brown <len.brown@intel.com>
Fri, 4 Jun 2010 19:22:18 +0000 (15:22 -0400)
commit157317ba3ec3e5a4d9683b8d24ba40b4f8f3296b
tree60cc7c2c5138837d25221e22cbd6ba966822b01f
parent67a3e12b05e055c0415c556a315a3d3eb637e29e
ACPI: Fix the incorrect calculation about C-state idle time

The C-state idle time is not calculated correctly, which will return the wrong
residency time in C-state. It will have the following effects:
   1.  The system can't choose the deeper C-state when it is idle next time.
Of course the system power is increased. E.g. On one server machine about 40W
idle power is increased.
   2.  The powertop shows that it will stay in C0 running state about 95% time
although the system is idle at most time.

2.6.35-rc1 regression caused-by: 2da513f582a96c053aacc2c92873978d2ea7abff
(ACPI: Minor cleanup eliminating redundant PMTIMER_TICKS to NS conversion)

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reported-by: Yu Zhidong <zhidong.yu@intel.com>
Tested-by: Yu Zhidong <zhidong.yu@intel.com>
Acked-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Len Brown <len.brown@intel.com>
drivers/acpi/processor_idle.c